This disclosure concerns a method and apparatus for holding or inspecting an end surface of an optical connector, wherein the connector includes a housing holding an optical ferrule with an optical fiber. In particular, this disclosure addresses a method and apparatus for fixing relative rotation between an optical connector and an inspection machine.
Optical connectors, including a housing holding the optical ferrule with an optical fiber, have end faces or surfaces that need to be a certain, optimum shape to prevent misalignments, air gaps, reflections, or scattering of light at interfaces at which optical fibers need to be coupled in an optical fiber link. Because of the precision needed, the end faces of optical connectors need to be inspected. Imperfections in the end faces of optical connectors are compounded by being summed with similar imperfections at other fiber junctions in the system and ultimately can lead to greatly increased light attenuation, lower signal to noise ratios, and lower system band width.
In some systems, to help preserve band width, connectors have been developed with angled cuts. In these types of arrangements, the ferrule is angle ground and then polished. Such angled polished connectors help to reduce incidents of back reflection. Back reflection is caused by two mating fiber ends that do not achieve physical contact with each other, creating a small air gap in the transmission path of the signal, which leads to back reflection of the laser light from the unmatched interface. To assure the necessary physical contact between two mating fibers, the ends can be angled and polished, as described above, and factors such as radius of curvature, fiber height, and apex offset of the polish with respect to the center of the fiber is controlled. These types of parameters will help to insure physical contact between the fibers, thereby minimizing loss and back reflection.
Before these connectors are installed in the field, they need to be inspected to measure, for example, the radius of curvature, the apex offset, and the fiber height. Various inspection machines have been developed for providing this type of testing. In general, these machines utilize interferometer based systems. One machine is commercially available from Direct Optical Research Company (DORC) of Phoenix, Ariz. The DORC machine uses an interferometer with a parfocal, parcentral zoom lens to inspect and measure an end surface of an optical fiber connector. DORC machines support the connector on a stage that is movable about three axes (X, Y, and Z axes) and the interferometer is set to a microscope mode. Controls of the stage along the X, Y, and Z axes are adjusted to bring the end surface into focus and alignment with the optical axis of the interferometer. The DORC machine also has a tilt stage that can be oriented to facilitate measurement of an angle on the end surface or protrusion or undercut of fiber with respect to the ferrule of a connector without readjusting the main stage. Further details about the DORC machine are described in U.S. Pat. No. 5,459,564 issued Oct. 17, 1995, and U.S. Pat. No. 6,215,555 issued Apr. 10, 2001, each of which is incorporated by reference herein.
Improvements in methods and apparatus for inspecting connector ends are desirable.
In general, methods and apparatus are provided for improving ways to hold or inspect an end surface of an optical connector. In particular, methods and apparatus are provided to fix relative rotation between an optical connector (about an axis that runs longitudinally through the optical connector) and an inspection machine.
In one method, in accordance with principles of the invention, an inspection machine is provided that includes a connector receipt aperture and a fixture defining a void. The optical connector is releasably secured to a cage member. The cage member preferably includes an extending flange. The optical connector is mounted into the inspection machine by inserting the end surface of the connector into the connector receipt aperture of the machine, and orienting the optical connector with the cage member to position the extending flange within the void of the fixture.
Also in accordance with principles of the invention, a cage member for an optical connector is disclosed. The cage member is provided for holding or fixing the relative rotation between the optical connector and an inspection machine. Preferably, the cage member comprises a frame defining an optical connector receiving chamber and having a longitudinal axis. The cage member also preferably includes a latch assembly that extends from the frame and is positioned adjacent to the receiving chamber. Further, the cage member preferably includes a flange that is cantilevered from the frame and oriented generally normal to the longitudinal axis. The flange will be arranged to be long enough such that it extends and fits into a receiving void fixed on the inspection machine.
Also, in accordance with principles of this disclosure, a mounting plate is provided.
Further, in accordance with principles of this disclosure, a combination of an optical connector and a cage member are provided.
In another aspect, this disclosure provides a kit for use with an inspection machine for inspecting an end surface of an optical connector. The kit includes a plate and a cage member. Preferably, the plate is constructed and arranged to be mounted on the inspection machine. The plate has an edge that defines a receiving void. The cage member is constructed and arranged to receive an optical connector. The cage member preferably includes an extending flange. The extending flange is sized to project into and be received by the receiving void of the plate.
Further, in accordance with principles of this disclosure, a mounting arrangement for use with an inspection machine for inspecting an end surface of an optical connector includes a cradle; a jig supported by the cradle; a chuck within the jig; a fixture mounted on the jig; the fixture defining a receiving void; and an optical connector mounted in a cage member. The optical connector includes a housing holding an optical ferrule with an optical fiber. The optical connector is mounted within, and held by, the chuck. The cage member includes an extending flange, and the extending flange is received within the receiving void of the fixture.